FIGS. 1 and 2 respectively illustrate a tape storage media 10, and a tape storage cartridge 20. Tape storage media 10 is contained with a shell housing 21 of tape storage cartridge 20 that is adapted to interface with a tape drive (not shown).
Specifically, tape cartridge 20 includes exterior cartridge shell 21 and sliding door 22. Sliding door 22 is slid open when tape cartridge 20 is inserted into a tape drive (not shown). Sliding door 22 is normally closed when tape cartridge 20 is not in use, so that debris and contaminants do not enter tape cartridge 20 and degrade tape storage media 10. The direction that tape cartridge 20 is slid into the tape drive is shown as direction 25. Tape cartridge 20 also contains a cartridge memory 24, which is on a printed circuit board 23. Cartridge memory 24 is preferably at a 45° angle, to allow the tape drive and pickers of an automated storage library (not shown) to access the contents of cartridge memory 24.
Tape storage media 10 includes a tape reel 11, which is prevented from rotation by a brake button 12 when tape cartridge 20 is not inserted in the tape drive. The tape drive releases brake button 12 when tape cartridge 20 is inserted into the tape drive, which then allows the free rotation of tape reel 11. Tape reel 11 is wound with tape 15, which is preferably magnetic tape. Alternatively, tape 15 could equally be magneto-optical or optical phase-change tape. On the free end of tape 15 is an optional leader tape 13 and leader pin 14. When tape cartridge 20 is slid into the tape drive, sliding door 22 is opened, and the tape drive threads leader pin 14 and attached leader tape 13 and tape 15 through the tape path. Tape 15 may be a data tape or a cleaner tape. Tape 15 may use the identical formulation of tape for both data and cleaning purposes. The contents of cartridge memory 24 are used to distinguish tape cartridge 20 as either a data cartridge or a cleaner cartridge. Optional leader tape 13 is preferably a thicker section of tape 15 which better withstand the load/unload operations of the tape drive.
Servo tracks 16 are recorded on tape 15 to facilitate an advantageous execution of a servo control of tape 15. FIG. 3 illustrates an exemplary N-pattern timing based servo 30 recordable on tape 15 within servo tracks 16 where servo 30 is shown as having four (4) N-pattern servo frames SF31-SF34. Each servo frame SF31-SF34 sequentially includes from left to right a trailing magnetic forward-slash stripe (/), a middle magnetic backward-slash stripe (\) and a leading magnetic forward-slash stripe (/). A servo element of a tape I/O head (not shown) makes a track 35 across servo frames SF31-SF34 as shown.
A velocity V of tape 15 is important to a reading or a writing of tape 15. Currently, a measurement of the velocity V of tape 15 is on a servo frame by servo frame basis involving a distance between the leading magnetic forward-slash stripe (/) and the trailing magnetic forward-slash stripe (/) of each servo frame divided by a traversal time of the distance between the leading magnetic forward-slash stripe (/) and the trailing magnetic forward-slash stripe (/) of each servo frame. The following equation [1] is a known first-order velocity calculation for servo frames SF31-SF34:V(j)=[D(j)−D(j−1)]/h+h*D″/2!  [1]where h is a time period between samples, j is a time index representing discrete increments in time, D(j)−D(j−1) is the linear distance across forward-slash stripes of a servo frame at time index j, D″(j) is a second derivative of D(j), and ! is the factorial function. The term h*D″/2! in equation [1] is the error term, and it is a function of h to the first power.
FIG. 4 illustrates an optical storage media 40, which may be Digital Versatile Disk (DVD), High Definition DVD (HD-DVD), Ultra Density Optical (UDO), Blu-Ray, or Holographic media. Optical storage media 40 shows four (4) servo sectors 41-44 and four (4) data sectors 45-48, and FIG. 5 illustrates a banded servo 50 recordable within each servo sector 41-44 where servo 50 is shown as having four (4) servo frames SF51-53 in zone A, and two (2) servo frames SF54 and SF55 in a zone B. An angular velocity ω of media 40 is important to a reading or a writing of media 40. Currently, a measurement of the angular velocity ω of media 40 is on a servo frame by servo frame basis involving an angular distance between ID fields (“IDF”) of two adjacent servo frames θ(j))−θ(j−1) divided by a traversal time h of the distance between the ID fields of the adjacent servo frames. The following equation [2] is a known first-order velocity calculation for servo frames SF51 -SF55:ω(j)=[θ(j)−θ(j−1)]/h+h*θ″/2!  [2]where h is a time period between samples, j is a time index representing discrete increments in time, θ(j) is a distance across legs of servo frame at time index j, and θ″(j) is a second derivative of θ(j); and ! is the factorial function. The term h*θ″/2! in equation [2] is the error term, and it is a function of h to the first power.
While equations [1] and [2] have proven be beneficial in calculating a velocity of a storage media, the storage media industry is constantly striving to improve the velocity calculations of storage media.